1. Field of the Invention
The present invention relates to a hollow fiber blood-processing device used for blood processing such as hemodialysis, hemofiltration, hemodiafiltration, plasma fraction and plasmapheresis, and a method for packaging and sterilizing such devices.
2. Description of Related Art
It is known that hollow fibers used as filters or semipermeable membranes in the blood-processing devices are generally damaged by radiation sterilization, resulting in increase of eluting materials or extractables from the hollow fibers. In particular, the hollow fibers of polysulfone-based resins including hydrophilic polymer have a high tendency to be damaged by irradiation. The extractables from the hollow fibers are measured by absorbance of a test solution for extraction, of which measuring procedures and criterion measure are defined in approval standards for artificial kidneys. In the standard, a test solution for extraction is prepared by placing 1.5 g of dry hollow fibers cut to a length of 2 cm and 150 mL of distilled water for injection in a glass container that meets alkali elution test defined in “Test procedures for glass containers for injections” in “The Japanese Pharmacopoeia Fourteenth Edition; warming the solution at 70±5° C. for 1 hour, cooling the solution to the room temperature, removing the hollow fibers from the solution, and then adding distilled water to the solution to adjust its volume to 150 ml. The absorbance is determined at the maximum absorption length within the range of 220 to 350 nm by ultraviolet absorption spectrum of the solution. The criterion measure for absorbance is set to 0.1 or below.
Up to now, there have been proposed a few methods for preventing hollow fibers of the hollow fiber blood-processing devices from being damaged by radiation sterilization. For example, Japanese patent laying-open No. JP2000-288085A (Patent document 1) discloses a method for preventing hollow fibers from being damaged by irradiation, which comprises the steps of controlling a water content of hollow fibers to ≦5%, and a relative humidity of ambient atmosphere to ≦40% when carrying out radiation sterilization. Japanese patent laying-open No. JP2001-170167A (Patent document 2) discloses a method that comprises the steps of allowing hollow fibers to hold water accounting for 100 to 600% of the whole weight of the hollow fibers, and filling the blood-processing device with inert gas. Japanese patent publication No. H5-50946 (B) discloses a method comprising the steps of sealing a blood-processing device together with deoxidizer in a gas-impermeable container, and then subjecting the resultant sealed container to radiation sterilization.    Patent document 1: JP2000-288085A    Patent document 2: JP2001-170167A    Patent document 3: JP H05-050946B